EthMultiCall_RPC.go.patch

From 7a70eb6ccb99eb242b066e23026de41f3bf70561 Mon Sep 17 00:00:00 2001
From: Levi Aul <levi@leviaul.com>
Date: Sat, 2 Oct 2021 13:45:42 -0700
Subject: [PATCH] Add eth_multicall API endpoint

---
 cmd/rpcdaemon/commands/eth_multicall.go | 174 ++++++++++++++++++++++++
 internal/web3ext/web3ext.go             |   6 +
 2 files changed, 180 insertions(+)
 create mode 100644 cmd/rpcdaemon/commands/eth_multicall.go

diff --git a/cmd/rpcdaemon/commands/eth_multicall.go b/cmd/rpcdaemon/commands/eth_multicall.go
new file mode 100644
index 0000000000..d62159f562
--- /dev/null
+++ b/cmd/rpcdaemon/commands/eth_multicall.go
@@ -0,0 +1,174 @@
+package commands
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/holiman/uint256"
+	common2 "github.com/ledgerwatch/erigon-lib/common"
+	"github.com/ledgerwatch/erigon/common"
+	"github.com/ledgerwatch/erigon/common/hexutil"
+	"github.com/ledgerwatch/erigon/common/math"
+	"github.com/ledgerwatch/erigon/core"
+	"github.com/ledgerwatch/erigon/core/rawdb"
+	"github.com/ledgerwatch/erigon/core/state"
+	"github.com/ledgerwatch/erigon/core/vm"
+	"github.com/ledgerwatch/erigon/ethdb"
+	"github.com/ledgerwatch/erigon/internal/ethapi"
+	"github.com/ledgerwatch/erigon/rpc"
+	"github.com/ledgerwatch/erigon/turbo/rpchelper"
+	"github.com/ledgerwatch/erigon/turbo/shards"
+	"github.com/ledgerwatch/erigon/turbo/transactions"
+	"github.com/ledgerwatch/log/v3"
+)
+
+type MulticallRunlist map[common.Address][]hexutil.Bytes
+
+type MulticallResult map[common.Address][]*MulticallExecutionResult
+
+type MulticallExecutionResult struct {
+	UsedGas    uint64
+	ReturnData hexutil.Bytes `json:",omitempty"`
+	Err        string        `json:",omitempty"`
+}
+
+// Call implements eth_call. Executes a new message call immediately without creating a transaction on the block chain.
+func (api *APIImpl) Multicall(ctx context.Context, commonCallArgs ethapi.CallArgs, contractsWithPayloads MulticallRunlist, blockNrOrHash *rpc.BlockNumberOrHash, overrides *map[common.Address]ethapi.Account) (MulticallResult, error) {
+	startTime := time.Now()
+
+	// result stores
+	execResults := make(MulticallResult)
+
+	dbtx, err := api.db.BeginRo(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer dbtx.Rollback()
+
+	chainConfig, err := api.chainConfig(dbtx)
+	if err != nil {
+		return nil, err
+	}
+
+	var baseFee *uint256.Int
+	if blockNrOrHash == nil {
+		var num = rpc.LatestBlockNumber
+		blockNrOrHash = &rpc.BlockNumberOrHash{BlockNumber: &num}
+	}
+	blockNumber, hash, err := rpchelper.GetBlockNumber(*blockNrOrHash, dbtx, api.filters)
+	if err != nil {
+		return nil, err
+	}
+	blockHeader := rawdb.ReadHeader(dbtx, hash, blockNumber)
+	if blockHeader == nil {
+		return nil, fmt.Errorf("block header %d(%x) not found", blockNumber, hash)
+	}
+	if blockHeader != nil && blockHeader.BaseFee != nil {
+		var overflow bool
+		baseFee, overflow = uint256.FromBig(blockHeader.BaseFee)
+		if overflow {
+			return nil, fmt.Errorf("header.BaseFee uint256 overflow")
+		}
+	}
+
+	var stateReader state.StateReader
+	if num, ok := blockNrOrHash.Number(); ok && num == rpc.LatestBlockNumber {
+		stateReader = state.NewPlainStateReader(dbtx)
+	} else {
+		stateReader = state.NewPlainState(dbtx, blockNumber)
+	}
+	stateCache := shards.NewStateCache(32, 0 /* no limit */)
+	cachedReader := state.NewCachedReader(stateReader, stateCache)
+	noop := state.NewNoopWriter()
+	cachedWriter := state.NewCachedWriter(noop, stateCache)
+	vmConfig := vm.Config{}
+
+	// Setup context so it may be cancelled the call has completed
+	// or, in case of unmetered gas, setup a context with a timeout.
+	var cancel context.CancelFunc
+	if callTimeout > 0 {
+		ctx, cancel = context.WithTimeout(ctx, callTimeout)
+	} else {
+		ctx, cancel = context.WithCancel(ctx)
+	}
+
+	// Make sure the context is cancelled when the call has completed
+	// this makes sure resources are cleaned up.
+	defer cancel()
+
+	callArgsBuf := commonCallArgs
+	callArgsBuf.MaxFeePerGas = (*hexutil.Big)(blockHeader.BaseFee)
+
+	if callArgsBuf.Gas == nil || uint64(*callArgsBuf.Gas) == 0 {
+		callArgsBuf.Gas = (*hexutil.Uint64)(&api.GasCap)
+	}
+
+	ibs := state.New(cachedReader)
+	var execSeq int
+
+	contractHasTEVM := ethdb.GetHasTEVM(dbtx)
+
+	for contractAddr, payloads := range contractsWithPayloads {
+		callArgsBuf.To = &contractAddr
+
+		execResultsForContract := make([]*MulticallExecutionResult, 0, len(payloads))
+
+		for _, payload := range payloads {
+			if err := common2.Stopped(ctx.Done()); err != nil {
+				return nil, err
+			}
+
+			callArgsBuf.Data = (*hexutil.Bytes)(&payload)
+
+			msg, err := callArgsBuf.ToMessage(api.GasCap, baseFee)
+			if err != nil {
+				return nil, err
+			}
+
+			blockCtx, txCtx := transactions.GetEvmContext(msg, blockHeader, blockNrOrHash.RequireCanonical, dbtx, contractHasTEVM)
+			blockCtx.GasLimit = math.MaxUint64
+			blockCtx.MaxGasLimit = true
+
+			evm := vm.NewEVM(blockCtx, txCtx, ibs, chainConfig, vmConfig)
+			gp := new(core.GasPool).AddGas(msg.Gas())
+
+			// Clone the state cache before applying the changes, clone is discarded
+			ibs.Prepare(common.Hash{}, blockHeader.Hash(), execSeq)
+
+			execResult, applyMsgErr := core.ApplyMessage(evm, msg, gp, true /* refunds */, true /* gasBailout */)
+
+			var effectiveErrDesc string
+			if applyMsgErr != nil {
+				effectiveErrDesc = applyMsgErr.Error()
+			} else if execResult.Err != nil {
+				effectiveErrDesc = ethapi.NewRevertError(execResult).Error()
+			}
+
+			if err = ibs.FinalizeTx(evm.ChainRules, noop); err != nil {
+				return nil, err
+			}
+			if err = ibs.CommitBlock(evm.ChainRules, cachedWriter); err != nil {
+				return nil, err
+			}
+
+			mcExecResult := &MulticallExecutionResult{
+				UsedGas: execResult.UsedGas,
+				Err:     effectiveErrDesc,
+			}
+
+			if len(execResult.ReturnData) > 0 {
+				mcExecResult.ReturnData = common.CopyBytes(execResult.ReturnData)
+			}
+
+			execResultsForContract = append(execResultsForContract, mcExecResult)
+			execSeq++
+		}
+
+		execResults[contractAddr] = execResultsForContract
+	}
+
+	log.Info("Executed eth_multicall", "runtime_usec", time.Since(startTime).Microseconds())
+
+	return execResults, nil
+}
diff --git a/internal/web3ext/web3ext.go b/internal/web3ext/web3ext.go
index a47e1ee074..ea33afae62 100644
--- a/internal/web3ext/web3ext.go
+++ b/internal/web3ext/web3ext.go
@@ -478,6 +478,12 @@ const EthJs = `
 web3._extend({
 	property: 'eth',
 	methods: [
+		new web3._extend.Method({
+			name: 'multicall',
+			call: 'eth_multicall',
+			params: 3,
+			inputFormatter: [web3._extend.formatters.inputCallFormatter, null, web3._extend.formatters.inputDefaultBlockNumberFormatter]
+		}),
 		new web3._extend.Method({
 			name: 'chainId',
 			call: 'eth_chainId',